"usambara" A bad name...?

[MizM]

I read that one is only found in higher elevations... I have since forgotten which one. Perhaps the color morph developed to make it less visible to predators at the different elevation?

 

[Wade]

Originally posted by skinheaddave

I'd like to know a lot more about their natural population dynamics before damning crossing between the two colour morphs -- and experimental crossing might go a long way towards interpreting population dynaimcs if they are properly studied.

Cheers,
Dave

I'm not damning the crossing out of hand, but I think it should be done with greater understanding of these spiders than we have now, unless we're talking experiments that never leave the "lab". It is not known for sure that P. murinus is just a highly variable species with intergrades all throughout the range...like your E. obsoleta example. If this turns out to be the case, I don't see anything wrong with selective breeding to ephisize certain traits, like vividness of coloration, etc. I'm still not sure if it's a great idea to cross distant populations, consider, for example, crossing the black rat with the everglades.

Sometimes populations become seperate from one annother, resulting in different forms evolving. If the orange form of P. murinus is, indeed, a seperate population from the yellow, than crossing them would be a very bad thing if these spiders got into the hobby. As an example, consider the Indian/Burmese (P.m.morlus/P.m.bivattatus) python fiasco. These are geogaphically seperate subspecies with no naturally occuring intergrades. The Indian was listed on CITES (appendix I, I think) which restricted it from being shipped accross state and international lines. Breeders dodged this by crossing it with the Burmese, resulting in the Indian being lost to the hobby (at least in the US).

Unlike NA ratsnakes (where population dynamics are fairly well understood), P. murinus comes from an area that's poorly studied and often has awful political circumstances that make proper field research difficult if not impossible. It will probably be awhile before we have a real handle on this spider's range and how the colors change over it. Until then, better safe than sorry IMO.

It's true that the naming of subspecies is falling out of favor in many circles, and for the most part I agree, otherwise things get unecesarily confusing and meaningless (we have a "greenish rat snake" which is an intergrade between the black and the yellow. It's sometimes referred to as "Elaphe obsoleta obsoleta x quadrivitta!") However, if a subspecies is geographically seperate from the main population, then I think having this reflected in a name is appropriate.

I'm not entirely sure how crossing them would help us understand population dynamics, but I have no problem with that sort of thing as long as it's done with the understanding that the spiders should never enter the hobby. Personally, I don't have time to mess around with breeding something that I can't sell or even give away in good conscience, but if sombody wants to do so with a scientific purpose in mind, go for it.

I'll admit that I'm not fully up on gentics or the finer points of snake breeding to really argue about how it relates to the coloration of spiders. I've got nothing against the designer snake scene (I'm more of a naturalist myself), I tend to feel that anything that gets people excited about science or nature (and away from passive entertainment) is a good thing.

Wade

 

[skinheaddave]

Wade,

I think we are in agreement over many points. Certainly, I would agree that messing with distant populations could lead to problems. That being said, genetic distance, geographical distance and observable difference are often three entirely different things and unless you happen to have a genetics lab at your disposal, seperating them out will often involve some x-breeding.

I actualy just had a thought. Is there anyone out there who has kept and bred both variants? If this were done, you would effectively have a common garden experiment and this could go a great way towards determining genetic vs. environmental influence on colouration.

Cheers,
Dave

 

[Professor T]

Originally posted by Mister Internet
Dave,

Interesting thoughts... I read quite a bit about Corn Snake genetics last year, which is a bit different. Basically, you have NO naturally occuring aberrant color morphs (barring albino and mutations) that are self-sustaining. The only localized color morph is the "Okeetee" color morph, which is no more than an extremely brilliant normal coloring/patterning. ALL the "designer" snakes (Butter Cream, Peppermint, Caramel, Charcoal, etc etc) are selective breedings of select mutations. I'm under no delusions that it would be this easy to manipulate T genes, but your questions about environment, locality, and other factors raise interesting possibilities.

Mr. Internet,

Not sure where you got your information on "corn snake" genetics, but its incorrect. FYI the "Okeetee" is not the only localized color morph. Many of the color morphs were found on the west coast of Florida, naturally occuring, between Tampa and Naples.

Basically, you have MANY naturally occuring aberrant color morphs in Elaphe guttata guttata. So, naturally occuring color morphs in tarantulas isn't different than the "corn snake" scenario. I hope this helps clear up your misconception. Nothing personal, just wanted to set the genetics record straight.

 

[Professor T]

Originally posted by Wade
Cross breeding to see what happens is one thing, but is quite annother to sell or otherwise allow the resulting spiders to enter the trade. If Tom's suggestion is correct, and it's an either-or type thing, then the crossed spiders would end up being identified as whichever parent they look like. If you're a T breeder, you might want to breed the Mombassa (since it's not as common in the hobby as the Usambara), so you breed what you think are pure Mombassas, but when they emerge half the slings are orange! Personally, I'd be pretty PO'd! Also, down the line annother taxonomist may come along and revise the whole thing and want to call the Usambaras a subspecies (subspecies are not popular among T taxonmists at the present time, but that could change), then we are talking hybrids.

Wade

Wade,

A hybrid is a cross between two different species, like a female horse crossed with a male donkey to make a mule. The mule is a hybrid animal.

A cross between two subspecies does not result in a hybrid, since they are the same species, just different races of that species.

But regardless of how picky I get with genetics terminology, I agree 100% with you in the value of keeping the subspecies distinct.

 

[Wade]

Dave-

I think we're pretty much in total agreement. Anyone doing real genetics research isn't going to be selling their crossed bred spiders into the hobby. My concern is a bored or lazy hobbyists who simply wants to try breeding the two together, either because they don't want to go to the trouble of finding the correct breeding stock, or else to create some new morph to sell, perhaps even claiming it to be a new species.

I've bred the orange variant several times, but never the golden. Despite all my hand wringing over the subject, I'm frankly surprised no ones already done it, it may have already happened. I do seem to remember somone on one of the lists suggesting that they could not be crossed, which would be a strong argument for distict species if it's true.

Prof. T-

You are right about the use of the word "hybrid". True hybrids, like your mule example, are generally sterile, correct?

The term would definately not apply to the P. murinus situation, but we often use the term to describe crosses between animals currently recognized as distict species, such as B. smithi and B. vagans. I believe the resulting spiders may be fertile. My understanding of the rules suggests that, from a taxonomic point of view, this would indicate that these are not seperate species, but simply a single, highly variable species. When T people get worked up over hybrids, we're concerned about the fertile crosses (that may not be true hybrids). If they were infertile, like the mule, the experiment would end with that generation and there would be no lasting negative result, because if it can't reproduce, it can't effect the gene pool.

Whew! We've almost beaten this topic to death, yet again. Ahhh, hybrids...

Wade

 

[skinheaddave]

Wade,

Yeah. So much for conflict. Someday if I have the opportunity, I may indeed try just such an experiment. Until then, I will keep my eyes out for further info others have gathered.

Originally posted by Wade
I believe the resulting spiders may be fertile. My understanding of the rules suggests that, from a taxonomic point of view, this would indicate that these are not seperate species, but simply a single, highly variable species.

Yes and no. There are many different ways of defining and determining what constitutes a species. The one that is in favour now is generally the biological species concept which states, quite simply, that reproductive isolation is the yardstick by which we measure what constitutes a species. There are, however, some provisos attached to the use of such a system. These include the fact that it must be considered under natural conditions and only on a short time scale -- really a snapshot in evolutionary terms. With enough persuasion and interference, there are lots of species which could probably produce fertile offspring. This is not, however a fair indication that they are the same species, as it is not under natural conditions. If, however, it was found that they could not x-breed, then that would constitute evidence of reproductive isolation at the genetic level and thus that speciation had occured.

And yes, we are probably flogging a dead horse at this point -- but if you crossed the dead horse with a very much alive donkey and then took the F1 generation and ...

Cheers,
Dave

 

[Professor T]

Originally posted by Wade


Prof. T-

You are right about the use of the word "hybrid". True hybrids, like your mule example, are generally sterile, correct?

The term would definately not apply to the P. murinus situation, but we often use the term to describe crosses between animals currently recognized as distict species, such as B. smithi and B. vagans. I believe the resulting spiders may be fertile. My understanding of the rules suggests that, from a taxonomic point of view, this would indicate that these are not seperate species, but simply a single, highly variable species. When T people get worked up over hybrids, we're concerned about the fertile crosses (that may not be true hybrids). If they were infertile, like the mule, the experiment would end with that generation and there would be no lasting negative result, because if it can't reproduce, it can't effect the gene pool.

Whew! We've almost beaten this topic to death, yet again. Ahhh, hybrids...

Wade

Wade,

You are correct that the mule is a sterile hybrid, and that many hybrids are sterile. However, not ALL hybrids are sterile. The cross between a coyote and a dog, known as the "coy-dog" is not sterile. A cross between a wolf and a dog is not a sterile hybrid either, and often is more aggressive toward humans than a wolf or a dog. The cross between a striped bass and a white bass isn't sterile.

Sometimes a single species has a wide genotypic and phenotypic varience from one extreme part of its range to the other. The races at the extremes can't interbreed, but they can both interbreed with races of that species inbetween. This "cline" can be the start of a new species.

Genetics is amazing!

 

[Steve Nunn]

Originally posted by sunnymarcie
..............Sorry if I hijack your thread!.............

It's all yours guys, I got the answer I was looking for.;P

Every time this topic comes up this sort of thing happens, I enjoy it but I can understand a lot of people getting muddled brains because of it.

Aren't the different color forms known as P.murinus and P.murinus (RCP). RCP- red color phase?

Steve

 

[belewfripp]

Regarding the mating of a standard murinus color form with another from what I have heard from other enthusiasts the color you get depends on the pairing, but you don't get mutt cross-breeds, you get either one or the other. As has been noted, there is some variation, but this should seem normal, in almost every species of animal there are variations, not every one looks exactly the same, even of the same 'color type' or what have you. Interesting to note is that, from what I have heard, you can breed any color form of rosehair with any other color form of rosehair and the eggsac will have members of each different color form (red, pink and ugly, I mean brown) in the same eggsac.


Also regarding tarantula coloration I have heard of there being some actual pigmentation found in scorpions but so far with Ts I believe consensus is the coloration is not due to pigment but due to the actual molecular structure of the cuticle. So what we're talking about here is manipulating genes for cuticle structure rather than for pigmentation, and lord only knows if the two could be treated in a similar manner or not.


Adrian

 

[belewfripp]

Originally posted by Steve Nunn
Aren't the different color forms known as P.murinus and P.murinus (RCP). RCP- red color phase?

Steve

Yeah, red color phase or red color form.

Adrian

 

[belewfripp]

Re: usambara x mombassa

Originally posted by Professor T
You have a slightly different gene pool existing in two geographic races that natural selection produced. Why reverse in a generation what could have taken millions of years to produce?

Again from what I understand from what others have said, the problem with IDing Pterinochilus of any species is that over their ranges they show a marked variation. This is noted somewhat in TTKG by Schultz and Schultz. This means that usumbaras and mombasas haven't been geographically segregated into nice, neat population distributions, rather it is quite the opposite. It would be nice to hear from someone who has been to their habitat and could tell us just how closely in proximity different members of this species' color forms live.


Adrian

 

[Professor T]

Re: Re: usambara x mombassa

Originally posted by belewfripp
Again from what I understand from what others have said, the problem with IDing Pterinochilus of any species is that over their ranges they show a marked variation. This is noted somewhat in TTKG by Schultz and Schultz. This means that usumbaras and mombasas haven't been geographically segregated into nice, neat population distributions, rather it is quite the opposite. It would be nice to hear from someone who has been to their habitat and could tell us just how closely in proximity different members of this species' color forms live.

Adrian

Adrian,

It is my understanding that the "usambara" color morph is geographically isolated to the Usambara Mountains in Tanzania.

 

[belewfripp]

Ah yes, you're right of course, my mistake.

Adrian

 

[Steve Nunn]

Re: Re: Re: usambara x mombassa

Originally posted by Professor T
Adrian,

It is my understanding that the "usambara" color morph is geographically isolated to the Usambara Mountains in Tanzania.

Hi,
I was aware that P.murinus RCF (red color form) came from the Usamabra Range, but I didn't know it was an isolated population of P.murinus. What are the geographical barriers that seperate the two color forms? Have these been researched? Brent Hendrixson (USA) is studying vicariance biogeography at present and may know something about P.murinus, anyone communicating with him (this is his field for sure)??

Steve

 

[phoenixxavierre]

Originally posted by sunnymarcie
Ok a difference in color question makes me wonder.......
Is there a difference in color male vs. female?
Or are there just different phases of color?

The color was the first thing that caught my eye, I do
not want anymore plain brown T's

I think it's been said that males tend to have more yellow and females more reddish and orange.

Cheers,

Paul

 

[phoenixxavierre]

Here is some info from Gallon's revision:

Under P. murinus we see type material collected from Tanzania, Ugogo Region (also known as Dodoma), that was a male holotype of P. murinus.

Male holotype of P. hindei from Fort Hall, Kenya (Muranga). P. hindei has been synonymised with P. murinus for the same reasons as P. elevatus.

Male holotype of P. mamillatus from Tanzania. Due to the possession of a particular type of embolus, only found in P. murinus, and due to the size of the palpal bulb, this has also been synonymised as P. murinus.

P. elevatus (two males and a female) from Tette (Tete), Mozambique. P. elevatus was synonymised with P. murinus due to the shared spike setae on the margin of the maxill, shape of the embolus and shape of the spermathecae.

P. mamillatus from the Usambara region of Tanzania was redescribed in 2000 by Schmidt. Gallon felt that P. mamillatus was not satisfactorily distinguished from other members of the genus. Schmidt stated that the red coloration was species specific. Due to the shape of the spermathecae, the makeup and shape of the emboli and tibial apophysis, being that they are all species specific to P. murinus, brings Gallon to the conclusion that the base color of P. murinus is variable, ranging from bright orange through beige to dark grey. All color forms are morphologically identical and hence the subjective splitting of species based solely on coloration is considered artificial. At least this is Gallon's opinion.

In addition I'll note the distribution:

Eastern central Africa with a single record from south-western Angola. Occurs in Angola, Burundi, Democratic Republic of Congo (Zaire), Kenya, Mozambique, South Africa, Tanzania, Zambia and Zimbabwe.

And naturally occuring: This species constructs a dense, tubular, silken retreat beneath stones, logs, and houses. It can also live arboreally within hollow tree branches. It does not seem to construct burrows, but merely occupies and adapts existing cavities.

There's much more info, but I figured I would add that in.

All the best,

Paul